Myth: You should never use plastic in the microwave.

Reality: When certain plastic containers get hot, plasticizers (additives used to make them flexible) can dissolve in food. Some plasticizers, such as phthalates, have been linked to reproductive problems in laboratory animals, and some phthalates have been banned from children’s toys by the European Parliament. But “the effect on humans isn’t clear,” says Anuradha Prakash, Ph.D., an associate professor of food science at Chapman University, in Orange, California, and an authority on microwaves with the Institute of Food Technologists. Phthalates are commonly found in soft plastics, like the kind meat is wrapped in, and flexible containers, such as those used for take-out food and yogurt.

Not all plastics run the risk of contaminating hot foods, however. Containers labeled as microwave-safe have passed strict Food and Drug Administration (FDA) guidelines for resilience and can withstand repeated use. (Go to www.realsimple.com/foodcontainers for more information on the proper use of plastic containers.) As for the cellophane wrap that many people lay on top of food to reheat faster and prevent splatters, skip it. The phthalates could migrate to your dinner. Instead, place a vented microwave-safe plastic cover or a white paper towel over the dish.

Bottom Line: Toss the take-out and delicatessen containers and heat food in plastics that are labeled microwave-safe.